Cyclic spacer etching process with improved profile control

ABSTRACT

Embodiments described herein relate to methods for patterning a substrate. Patterning processes, such as double patterning and quadruple patterning processes, may benefit from the embodiments described herein which include performing an inert plasma treatment on a spacer material, performing an etching process on a treated region of the spacer material, and repeating the inert plasma treatment and the etching process to form a desired spacer profile. The inert plasma treatment process may be a biased process and the etching process may be an unbiased process. Various processing parameters, such as process gas ratios and pressures, may be controlled to influence a desired spacer profile.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit to U.S. Provisional Patent ApplicationNo. 62/140,243, filed Mar. 30, 2015, the entirety of which is hereinincorporated by reference.

BACKGROUND

1. Field

Embodiments of the present disclosure generally relate to methods ofpatterning and etching a substrate. More specifically, embodimentsdescribed herein relate to a cyclic spacer etching process with improvedprofile control.

2. Description of the Related Art

In response to an increased need for smaller electronic devices withdenser circuits, devices with three dimensional (3D) structures, such asfin field effect transistors (FinFETs) have been developed. Formingsub-10 nm node structures is desired but complicated by limitations andcomplexities associated with various patterning and lithographyprocesses.

For example, multiple patterning processes, such as self-aligned doublepatterning (SADP) and self-aligned quadruple patterning (SAQP)processes, may not adequately provide reliable patterning given thesmall pitch size requirements associated with formation of sub-10 nmnode structures. Other lithography processes, such aslitho-etch-litho-etch (LELE) processes which utilize 193 nm immersionphotolithography, may increase the line width roughness (LWR) of aresist used to pattern features on the substrate.

Conventional double and quadruple double patterning schemes generallyinvolve etching of a spacer material and removal of a mandrel materialto leave a mask pattern created by individual spacers. However,conventional spacer etching processes often result in asymmetric spacerprofiles. For example, a footing formed near the bottom of a spacerstructure may result from uneven plasma exposure and may also beinfluenced by polymer materials disposed on sidewalls of the spacerstructures to protect the sidewalls from undesirable etching.Inconsistencies and asymmetries in spacer etching may affect patterntransfer which can result in adjacent features having inconsistentcritical dimensions, depths, shapes, etc. Moreover, current lithographyand patterning processes are time consuming, which reduces throughputfor device processing.

Accordingly, what is needed in the art are improved patterning methods.

SUMMARY

In one embodiment, a method of patterning a substrate is provided. Themethod includes positioning a substrate having one or more mandrelstructures and a spacer material formed thereon in a processing chamber.The spacer material may be a layer formed over the mandrel structuresand the spacer material may be exposed to an inert plasma to modify oneor more regions of the spacer material. The modified regions of thespacer material may be exposed to an etchant plasma to remove a portionof the spacer material, and the exposing the spacer material to an inertplasma and the exposing the modified regions of the spacer material toan etchant plasma may be repeated until a portion of the mandrelstructure is exposed.

In another embodiment, a method of patterning a substrate is provided.The method includes positioning a substrate having one or more mandrelstructures and a spacer material formed thereon in a processing chamberand exposing the spacer material to a biased inert plasma at a pressureof less than about 300 milliTorr (mT) to modify one or more regions ofthe spacer material. The modified regions of the spacer material may beexposed to an unbiased etchant plasma generated by a remote plasmasource at a pressure of greater than about 500 mT to remove a portion ofthe spacer material. The exposing the spacer material to an inert plasmaand the exposing the modified regions of the spacer material to anetchant plasma may be repeated until a portion of the mandrel structureis exposed.

In yet another embodiment, a method of patterning a substrate isprovided. The method includes positioning a substrate having one or moremandrel structures and spacer material formed thereon in a processingchamber and exposing the spacer material to an inert plasma to modifyone or more regions of the spacer material. The modified regions of thespacer material may be exposed to an etchant plasma to remove a portionof the spacer material and the exposing the spacer material to an inertplasma and the exposing the modified regions of the spacer material toan etchant plasma may be repeated until a portion of the mandrelstructure is exposed. The mandrel structure may be etched and theexposing the spacer material to an inert plasma and the exposing themodified regions of the spacer material to an etchant plasma may berepeated until a desired spacer profile if formed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, may admit to other equally effective embodiments.

FIG. 1 illustrates a schematic, plan view of an exemplary processingsystem in which embodiments of the disclosure may be practiced.

FIG. 2 illustrates a partial cross-sectional view of a substrate havingmandrel structures and a spacer material formed thereon according to oneembodiment described herein.

FIG. 3 illustrates a partial cross-sectional view of the substrate ofFIG. 2 after performing a spacer material modification process accordingto one embodiment described herein.

FIG. 4 illustrates a partial cross-sectional view of the substrate ofFIG. 3 after performing an etching process according to one embodimentdescribed herein.

FIG. 5 illustrates a partial cross-sectional view of the substrate ofFIG. 4 after performing a cyclic spacer material removal processaccording to one embodiment described herein.

FIG. 6 illustrates a partial cross-sectional view of the substrate ofFIG. 5 after performing a mandrel structure etching process according toone embodiment described herein.

FIG. 7 illustrates a partial cross-sectional view of the substrate ofFIG. 6 after performing the cyclic spacer material removal processaccording to one embodiment described herein.

FIG. 8 illustrates a partial cross-sectional view of the substrate ofFIG. 7 after performing a mandrel structure removal process according toone embodiment described herein.

FIG. 9 illustrates a flow diagram of a method for processing a substrateaccording to embodiments described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments described herein relate to methods for patterning asubstrate. Patterning processes, such as double patterning and quadruplepatterning processes, may benefit from the embodiments described hereinwhich include performing an inert plasma treatment on a spacer material,performing an etching process on a treated region of the spacermaterial, and repeating the inert plasma treatment and the etchingprocess to form a desired spacer profile. The inert plasma treatmentprocess may be a biased process and the etching process may be anunbiased process. Various processing parameters, such as process gasratios and pressures, may be controlled to influence a desired spacerprofile.

A substrate having mandrel structures and a spacer material layerdisposed thereon may be processed according to the embodiments describedherein. The inert plasma treatment process may utilize acapacitively-coupled plasma and a suitable chemistry to modify regionsof the spacer material layer without removing portions of the spacermaterial. The inert plasma treatment process may be biased to controlmodification of desired regions of the spacer material layer. Anunbiased etching process may utilize a capacitively-coupled plasma witha suitable process gas to etch the modified regions of the spacermaterial in a cyclic manner by repeating the plasma treatment and plasmaetching processes until a desired spacer profile is achieved. Forexample, the cyclic modification and etching process may be performed toexpose the mandrel structures. A mandrel recess process may also beperformed and the cyclic modification and etching process may beperformed subsequent to the mandrel recess to further remove remainingundesirable spacer material.

FIG. 1 illustrates a schematic, plan view of a processing system 101which may be utilized to perform the methods described herein. Theprocessing system 101 may perform various processes, such as depositionprocesses, etching processes, and baking and curing processes, amongothers. The processing system 101 includes a pair of front openingunified pods 102. Substrates are generally provided from the frontopening unified pods 102. One or more first robots 104 retrieve thesubstrates from the front opening unified pods 102 and place thesubstrates into a loadlock chamber 106. One or more second robots 110transport the substrates from the loadlock chamber 106 to one or moreprocessing chambers 108 a-108 f. Each of the processing chambers 108a-108 f may be configured to perform a number of substrate processingoperations, such as plasma modification, plasma etching, epitaxial layerdeposition, atomic layer deposition (ALD), chemical vapor deposition(CVD), physical vapor deposition (PVD), pre-clean, degas, orientation,and other substrate processes.

The substrate processing chambers 108 a-108 f may include one or moresystem components for modifying and/or etching a material deposited on asubstrate. In one configuration, two pairs of the processing chambers,for example, 108 c-108 d and 108 e-108 f, may be used to modify amaterial on the substrate, and the third pair of processing chambers,for example, 108 a-108 b, may be used to remove material from thesubstrate. In another configuration, all of the processing chambers 108a-108 f may be configured to remove material from the substrate. In thisconfiguration, each pair of processing chambers, 108 a-108 b, 108 c-108d, 108 e-108 f, may be configured to perform a selective etchingprocess.

In one embodiment, processing chambers 108 a-108 b may be configured toselectively etch various spacer materials utilizing a dry plasma etchingprocess. Processing chambers 108 c-108 d may be configured toselectively etch semiconducting materials, such as silicon, silicongermanium, germanium, and III-V material, utilizing a dry plasma etchingprocess. Processing chambers 108 e-108 f may be configured to modifyspacer materials utilizing an inert plasma modification process. In oneembodiment, the processing chambers 108 e-108 f utilize an electron beamto form a plasma. However, other methods of forming a plasma may also beutilized. The processing system 101 described herein may be utilized toperform the processes described herein. Additionally, any one or more ofthe processes described herein may be performed in chamber(s) separatedfrom the processing system 101.

The above-described processing system 101 can be controlled by aprocessor based system controller such a controller 190. For example,the controller 190 may be configured to control flow of various processgases and purge gases from gas sources, during different operations of asubstrate process sequence. The controller 190 includes a programmablecentral processing unit (CPU) 192 that is operable with a memory 194 anda mass storage device, an input control unit, and a display unit (notshown), such as power supplies, clocks, cache, input/output (I/O)circuits, and the like, coupled to the various components of theprocessing system 101 to facilitate control of the substrate processing.The controller 190 also includes hardware for monitoring substrateprocessing through sensors in the processing system 101, includingsensors monitoring the process gas and purge gas flow. Other sensorsthat measure system parameters such as substrate temperature, chamberatmosphere pressure and the like, may also provide information to thecontroller 190.

To facilitate control of the processing system 101 described above, theCPU 192 may be one of any form of general purpose computer processorthat can be used in an industrial setting, such as a programmable logiccontroller (PLC), for controlling various chambers and sub-processors.The memory 194 is coupled to the CPU 192 and the memory 194 isnon-transitory and may be one or more of readily available memory suchas random access memory (RAM), read only memory (ROM), floppy diskdrive, hard disk, or any other form of digital storage, local or remote.Support circuits 196 are coupled to the CPU 192 for supporting theprocessor in a conventional manner. Material modification, etching, andother processes are generally stored in the memory 194, typically as asoftware routine. The software routine may also be stored and/orexecuted by a second CPU (not shown) that is remotely located from thehardware being controlled by the CPU 192.

The memory 194 is in the form of computer-readable storage media thatcontains instructions, that when executed by the CPU 192, facilitatesthe operation of the processing system 101. The instructions in thememory 194 are in the form of a program product such as a program thatimplements the method of the present disclosure. The program code mayconform to any one of a number of different programming languages. Inone example, the disclosure may be implemented as a program productstored on computer-readable storage media for use with a computersystem. The program(s) of the program product define functions of theembodiments (including the methods described herein). Illustrativecomputer-readable storage media include, but are not limited to: (i)non-writable storage media (e.g., read-only memory devices within acomputer such as CD-ROM disks readable by a CD-ROM drive, flash memory,ROM chips or any type of solid-state non-volatile semiconductor memory)on which information is permanently stored; and (ii) writable storagemedia (e.g., floppy disks within a diskette drive or hard-disk drive orany type of solid-state random-access semiconductor memory) on whichalterable information is stored. Such computer-readable storage media,when carrying computer-readable instructions that direct the functionsof the methods described herein, are embodiments of the presentdisclosure.

FIG. 2 illustrates a partial cross-sectional view of a substrate 202having mandrel structures 204 and a spacer material 206 formed thereonaccording to one embodiment described herein. The substrate 202 may beformed from suitable materials, such as semiconducting materials, oxidematerials, and the like. In other embodiments, the substrate 202 may bea material layer disposed on a substrate. The mandrels structures 204may be formed from various materials, including silicon containingmaterials, III-V materials, or the like. The spacer material 206 may beformed from suitable spacer or hardmask materials, such as siliconcontaining materials, nitride containing materials, and the like. Incertain embodiments, the spacer material 206 may be a silicon nitridematerial, a polysilicon material, or a titanium nitride material. It iscontemplated that the materials selected for the mandrel structures 204and the spacer material 206 may be suitable for use in the fabricationof FinFET structures. It is also contemplated that the materialsselected for the mandrel structures 204 and the spacer material 206 mayhave different characteristics to facilitate selective etchingprocesses.

Generally, the mandrel structures 204 may extend from the substrate 202and the spacer material 206 may be formed in a layer over the mandrelstructures 204 and the substrate 202. The spacer material 206 may bedeposited by various techniques, such as chemical vapor deposition(CVD), physical vapor deposition (PVD), or other suitable processes. Inone embodiment, the spacer material 206 may be predominantly conformallydeposited over the mandrel structures 204 and the substrate 202. Themandrel structures 204 may be spaced apart such that when the spacermaterial 206 is deposited, a trench 208 may be formed between adjacentmandrel structures. In the embodiments provided below, processingparameters are generally described with regard to the processing of a300 mm substrate, however, it is contemplated the other size substrates,such as 200 mm or 450 mm substrates, may benefit from the embodimentsdescribed herein.

FIG. 3 illustrates a partial cross-sectional view of the substrate 202of FIG. 2 after performing a spacer material modification processaccording to one embodiment described herein. The spacer material 206may be modified in an inert plasma modification process. The inertplasma modification process may utilize suitable chemistry to modify oralter the material properties of the spacer material 206 withoutremoving the spacer material 206. For example, the physical structure orthe chemical make-up of the spacer material 206 may be altered afterexposure to an inert plasma 302. In one embodiment, the spacer material206 is exposed to the inert plasma 302 to form modified regions 304 ofthe spacer material. The modified regions 304 of the spacer material 206are generally located at a top region 306 above the mandrel structure204 and a bottom region 308 within the trench 208. The inert plasma maybe generated by a remote plasma source or may be generated in situ inthe processing chamber. The inert plasma generation process may be aninductively coupled plasma process or a capacitively-coupled plasmaprocess. Generally, a bias may be utilized during the inert plasmamodification process to influence directionality of the plasma withregard to the spacer material 206. Suitable process gases for formingthe inert plasma 302 include noble gases, H₂, N₂, and O₂, among others.

Various processing parameters may also be controlled during the inertplasma modification process. For example, a capacitively-coupled biaspower may be between about 10 W and about 1500 W, such as between about50 W and about 200 W, for example, about 100 W. A pressure in theprocessing chamber during the inert plasma modification process may bemaintained between about 3 mT and about 300 mT, such as between about 10mT and about 100 mT, for example, about 20 mT.

In one embodiment, polysilicon may be utilized as the spacer material206 and a noble gas (He, Ne, Ar, Kr, Xe, Rn) may be utilized as aprocessing gas to modify the spacer material 206. In another embodiment,silicon nitride may be utilized as the spacer material 206 and a He orH₂ process gas may be utilized to modify the spacer material 206. In anembodiment utilizing He process gas, the He process gas may be providedto the process chamber at a flow rate of between about 300 sccm andabout 900 sccm, such as about 600 sccm. The inert plasma modificationprocess may be performed for a suitable amount of time to modify adesirable amount of spacer material 206.

FIG. 4 illustrates a partial cross-sectional view of the substrate 202of FIG. 3 after performing an etching process according to oneembodiment described herein. The etching process may be performed toremove the modified regions 304 formed in the inert plasma modificationprocess. The removed modified regions 304 are illustrated in FIG. 4 asdashed lines, indicating where the modified regions 304 existed prior toremoval during the etching process. The etching process is configured toexpose the modified regions 304 to an etchant plasma which is selectiveto the modified regions 304 as opposed to sidewalls 402 of the spacermaterial 206.

In one embodiment, the etchant plasma may be generated by a remoteplasma source. The etchant plasma may be unbiased and the etchingcharacteristics may be predominantly isotropic. However, the process gaschemistry utilized to form the etchant plasma may be configured toselectively remove the modified regions 304 relative to other regions ofthe spacer material 206, such as the sidewalls 402. Various processgases suitable for forming the etchant plasma include NF₃, NH₃, N₂, H₂,H₂O₂, O₂, Cl₂, F₂, and combinations and mixtures thereof. The processgases formed into the etchant plasma may be provided to the processingchamber in the presence of a carrier gas, such as He or Ar.

A power suitable for etchant plasma generation by a remote plasma sourcemay be between about 10 W and about 2000 W, such as between about 20 Wand about 100 W, for example, about 40 W. A pressure in the processingchamber during the etchant plasma process may be maintained betweenabout 500 mT and about 10 T, such as between about 1000 mT and about2000 mT, for example, about 1500 mT. In one embodiment, a siliconnitride spacer material modified with a He inert plasma may be etched bya combination of NF₃ and NH₃ process gases carried by He gas. In thisembodiment, a ratio of NF₃:NH₃:He may be between about 1:10:33.3. A flowrate of the NF₃ process gas may be between about 1 sccm and about 100sccm, such as between about 25 sccm and about 50 sccm, for example,about 30 sccm. A flow rate of the NH₃ process gas may be between about100 sccm and about 1000 sccm, such as between about 200 sccm and about400 sccm, for example, about 300 sccm. A flow rate of the He carrier gasmay be between about 100 sccm and about 5000 sccm, such as between about500 sccm and about 2000 sccm, for example, about 1000 sccm.

As a result of exposure of the modified regions 304 of the spacermaterial 206 to the etchant plasma, the modified regions 304 may beremoved. It is contemplated that less than an entire desirable amount ofspacer may be removed after performing the inert plasma modificationprocess and the etchant plasma material removal process. Accordingly,the inert plasma modification process and the etchant plasma materialremoval processes may be repeated in a cyclic manner until the mandrelstructure in exposed or until a desired profile of the spacer material206 is formed. It is contemplated that the process may be cycled one ormore times, for example, between about 2 times and about 100 times. Ifthe cyclic material modification and etching process form a desiredspacer profile, the substrate may by subsequently processed by variousother substrate processing operations.

FIG. 5 illustrates a partial cross-sectional view of the substrate 202of FIG. 4 after performing a cyclic spacer material removal processaccording to one embodiment described herein. Occasionally, the spacermaterial cyclic removal process may not remove all of the desired spacermaterial 206 after cyclic processing. For example, some spacer material206 may remain on the substrate 202 in the trench 208 at the bottomregion 308. It is believed that spacer material disposed in the topregion 306 may be etched and removed more quickly in the cyclic spacermaterial removal process when compared to spacer material removal withinthe trench 208. In this example, the spacer material 206 may be etchedby the cyclic material removal process until a top surface 502 of themandrels structures 204 is exposed and/or is substantially coplanar witha top surface 504 of the spacer material 206. It is believe that bycontrolling the pressure during the plasma etching operation of thecyclic spacer material removal process, the profile of the top surface504 may be predominantly planar.

FIG. 6 illustrates a partial cross-sectional view of the substrate 202of FIG. 5 after performing a mandrel structure etching process accordingto one embodiment described herein. In order to remove spacer material206 remaining in the bottom region 308 of the trench 208, the cyclicspacer material removal process may be performed again. However, tofurther control the profile of the spacer material 206, the mandrelstructures 204 may be etched to influence the plasma exposure duringmodification and etching by reducing the probability of asymmetricplasma exposure to the spacer material 206 at the top region 306.

The mandrel structures 204, which generally comprise a siliconcontaining material, may be etched by a combination of NF₃ and NH₃process gases carried by He gas. In this embodiment, a ratio ofNF₃:NH₃:He may be about 1:5:20. A flow rate of the NF₃ process gas maybe between about 1 sccm and about 100 sccm, such as between about 25sccm and about 50 sccm, for example, about 30 sccm. A flow rate of theNH₃ process gas may be between about 50 sccm and about 1000 sccm, suchas between about 100 sccm and about 300 sccm, for example, about 150sccm. A flow rate of the He carrier gas may be between about 100 sccmand about 5000 sccm, such as between about 400 sccm and about 1500 sccm,for example, about 600 sccm.

After etching the mandrel structures 204, the top surface 502 of themandrel structures 204 may be recessed below the top surface 504 of thespacer material 206.

FIG. 7 illustrates a partial cross-sectional view of the substrate 202of FIG. 6 after performing the cyclic spacer material removal processaccording to one embodiment described herein. The cyclic spacer materialremoval process may be performed to remove any remaining undesirablespacer material 206, such as the spacer material 206 remaining on thesubstrate 202 in the bottom region 308 of the trench 208 as illustratein FIG. 6. The cyclic spacer material removal process, described indetail with regard to FIGS. 3 and 4, may be performed for a suitablenumber of cycles to expose a top surface 702 of the substrate 202 andform a desirable spacer material profile. In certain embodiments, thetop surface 504 of the spacer material 206 may have a planar profile ora rounded profile, depending on the pressure maintained within theprocessing chamber when performing the spacer material etching process.

FIG. 8 illustrates a partial cross-sectional view of the substrate 202of FIG. 7 after performing a mandrel structure removal process accordingto one embodiment described herein. After the desired spacer materialprofile has been formed utilizing the cyclic spacer material removalprocess, the mandrel structures 204 may be removed. A mandrel materialetching process, described with regard to FIG. 6, or other suitableprocess may be utilized to remove the mandrel structures 204 from thesubstrate 202.

A pitch 802 of the features formed by the spacer material 206 may bebetween about 10 nm and about 40 nm, such as about 20 nm. Similarly, acritical dimension 804 of the spacer material features may be less thanabout 10 nm. Subsequent etching processes may be performed to transferthe pattern formed by the spacer material features to other materiallayers of the substrate 202.

FIG. 9 illustrates a flow diagram of a method 900 for processing asubstrate according to embodiments described herein. At operation 910, asubstrate having mandrel structures and a spacer material formed thereonmay be positioned in a processing chamber. The processing chamber may bea chamber suitable for performing plasma modification and plasma etchingprocesses, such as the chamber 101 described in FIG. 1. At operation920, the spacer material may be exposed to an inert plasma to modifyregions of the spacer material.

At operation 930, the modified regions of the spacer material maybeexposed to an etchant plasma. In one embodiment, operation 920 may beperformed in a first processing chamber, such as chambers 108 e-108 f,and operation 930 may be performed in a second processing chamber, suchas chambers 108 a-108 b. Transfer of the substrate between the firstprocessing chamber and the second processing chamber may be performed ina vacuum environment, such as through a transfer chamber. Alternatively,operations 920 and 930 may be performed in a single chamber.

At operation 940, operations 920 and 930 may be repeated until a desiredspacer material profile is achieved. By separating the modification andetching processes and controlling various processing conditions,directionality of the etching process may be improved and may result inan improved spacer material profile. For example, a substantially flator rounded spacer material profile may be achieved in conjunction withrecessing the mandrel to avoid asymmetric plasma exposure.

Moreover, spacer material footings may be avoided or reduced because apolymer protective layer to protect sidewalls of the spacer material isnot needed as a result of the improved spacer material etching controlwhen utilizing the cyclic spacer material removal processes describedherein. Thus, multiple patterning processes may benefit from theembodiments described herein and sub-10 nm node structures may bepatterned more effectively.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A method of patterning a substrate, comprising:positioning a substrate having one or more mandrel structures and aspacer material formed thereon in a processing chamber, wherein thespacer material is a layer formed over the mandrel structures; exposingthe spacer material to an inert plasma to modify one or more regions ofthe spacer material; exposing the modified regions of the spacermaterial to an etchant plasma to remove a portion of the spacermaterial; and repeating the exposing the spacer material to an inertplasma and the exposing the modified regions of the spacer material toan etchant plasma until a portion of the mandrel structure is exposed.2. The method of claim 1, wherein the one or more mandrel structurescomprise a silicon containing material.
 3. The method of claim 1,wherein the spacer material comprises a nitride containing material, anoxide containing material, a polysilicon material, a titanium nitridematerial, or combinations thereof.
 4. The method of claim 1, wherein thespacer material comprises polysilicon and the inert plasma is formedfrom a noble gas.
 5. The method of claim 1, wherein the spacer materialcomprises silicon nitride and the inert plasma is formed from aprocessing gas comprising helium or hydrogen.
 6. The method of claim 1,wherein a processing gas utilized to form the inert plasma is selectedfrom the group consisting of H₂, N₂, O₂, nobles gases, and combinationsand mixtures thereof.
 7. The method of claim 6, wherein a processing gasutilized to form the etchant plasma is selected from the groupconsisting of H₂, N₂, H₂O₂, NF₃, NH₃, Cl₂, F₂, and combinations andmixtures thereof.
 8. The method of claim 1, wherein exposing the spacermaterial to an inert plasma further comprises: biasing the substrate. 9.The method of claim 8, wherein the biasing the substrate is performed ata power of between about 10 W and about 1500 W.
 10. The method of claim8, wherein the exposing the spacer material to an inert plasma isperformed at a pressure of between about 5 mT and about 300 mT.
 11. Themethod of claim 1, wherein the etchant plasma exposure is unbiased andthe etchant plasma is generated by a remote plasma source.
 12. Themethod of claim 11, wherein a power utilized to generate the etchantplasma from the remote plasma source for a 300 mm substrate is betweenabout 20 W and about 2000 W.
 13. The method of claim 11, wherein theetchant plasma exposure is performed at a pressure of between about 500mT and about 10 T.
 14. A method of patterning a substrate, comprising:positioning a substrate having one or more mandrel structures and aspacer material formed thereon in a processing chamber, exposing thespacer material to a biased inert plasma at a pressure of less thanabout 300 mT to modify one or more regions of the spacer material;exposing the modified regions of the spacer material to an unbiasedetchant plasma generated by a remote plasma source at a pressure ofgreater than about 500 mT to remove a portion of the spacer material;and repeating the exposing the spacer material to an inert plasma andthe exposing the modified regions of the spacer material to an etchantplasma until a portion of the mandrel structure is exposed.
 15. Themethod of claim 14, wherein the exposing the exposing the spacermaterial to a biased inert plasma is performed in a first processingchamber and the exposing the modified region of the spacer material toan unbiased etchant plasma is performed in a second processing chamber.16. The method of claim 15, wherein the substrate is transferred fromthe first processing chamber to the second processing chamber withoutbreaking vacuum.
 17. The method of claim 14, wherein the exposing theexposing the spacer material to a biased inert plasma and the exposingthe modified region of the spacer material to an unbiased etchant plasmaare performed in a single chamber.
 18. A method of patterning asubstrate, comprising: positioning a substrate having one or moremandrel structures and a spacer material formed thereon in a processingchamber; exposing the spacer material to an inert plasma to modify oneor more regions of the spacer material; exposing the modified regions ofthe spacer material to an etchant plasma to remove a portion of thespacer material; repeating the exposing the spacer material to an inertplasma and the exposing the modified regions of the spacer material toan etchant plasma until a portion of the mandrel structure is exposed;etching the mandrel structure; and repeating the exposing the spacermaterial to an inert plasma and the exposing the modified regions of thespacer material to an etchant plasma until a desired spacer profile isformed.
 19. The method of claim 18, wherein exposing the spacer materialto an inert plasma further comprises: biasing the substrate.
 20. Themethod of claim 19, wherein the etchant plasma exposure is unbiased andthe etchant plasma is generated by a remote plasma source.